Massive pulmonary embolism masquerading as acute coronary syndrome.

Pulmonary embolism (PE) can be a challenging and fatal diagnosis, especially with a negative D-dimer test, which may lead to underestimation of PE risk. A 70-year-old woman presented with chest pain, breathlessness and orthostatic presyncope. Her electrocardiogram had antero-lateral ischaemic changes, with a troponin of 62, lactate 3.4 and negative D-dimer. She was treated as having acute coronary syndrome until she became hypoxaemic, hypotensive and tachycardic. Point-of-care echocardiography revealed a dilated right atrium containing an echogenic mass, moderate-to-severe tricuspid regurgitation, a dilated right ventricle and dilated inferior vena cava. McConnell's sign was positive. CT pulmonary angiogram confirmed a central PE, and she was thrombolysed with alteplase. Clinicians should be aware that central PEs can present with typical anginal symptoms, pre-syncope or syncope. A negative D-dimer test with an age-adjusted cut-off may help exclude PE in patients with low or intermediate clinical probability, but should not be used for higher-risk patients. In this case, echocardiography played a crucial role in the diagnosis.